title: Effect of water aging on microtensile bond strength of dual-cured resin cements to pre-treated sintered zirconium-oxide ceramics.
abstract: OBJECTIVE
  To evaluate the hydrolytic stability of different dual-cure resin cements when luted to zirconia ceramic.
  
  
  METHODS
  Eighteen cylinder-shaped zirconia blocks (Cercon Zirconia, Dentsply) were conditioned with: Group 1, no treatment; Group 2, sandblasting (125microm alumina-Al(2)O(3)-particles); Group 3, tribochemical silica coating (50microm silica-modified Al(2)O(3) particles). Ceramic blocks were duplicated in composite resin (Tetric Evo Ceram, Ivoclar-Vivadent). Composite disks were luted to pre-treated ceramic surfaces using: (1) Clearfil Esthetic Cement (CEC; Kuraray); (2) Rely X Unicem (RXU; 3M ESPE); (3) Calibra (CAL; Dentsply Caulk). After 24h, bonded samples were cut into microtensile sticks (1mm(2)). Half of the sticks were loaded in tension until failure (cross-head speed of 0.5mm/min). The remaining half was tested after 6 months of water storage at 37 degrees C. Data was analyzed with three-way ANOVA and Tukey's test (P<0.05). Fractographic analysis was performed by SEM.
  
  
  RESULTS
  After 24h, bond strength of CEC to zirconia was significantly higher than that of RXU and CAL, independently from the ceramic pre-treatment (P<0.001). Using CAL, all samples failed prematurely except when luting to sandblasted surfaces. After 6 months of water aging, bond strength of CEC significantly decreased. RXU did not significantly alter bond strengths. Adhesion of sandblasted specimens luted with CAL fell over time. Micromorphological alterations were evident after water storage.
  
  
  CONCLUSIONS
  Resin-ceramic interfacial longevity depended on cement selection rather than on surface pre-treatments. CEC and RXU were both suitable for luting zirconia. Water aging played an important role in the durability of zirconia-to-composite chemical bonds.
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, University Complutense of Madrid, Madrid, Spain. siete_rosas.rc@hotmail.com
authors.forename: Raquel Castillo
authors.initials: RC
authors.lastname: Oyagüe
authors.forename: Francesca
authors.initials: F
authors.lastname: Monticelli
authors.forename: Manuel
authors.initials: M
authors.lastname: Toledano
authors.forename: Estrella
authors.initials: E
authors.lastname: Osorio
authors.forename: Marco
authors.initials: M
authors.lastname: Ferrari
authors.forename: Raquel
authors.initials: R
authors.lastname: Osorio
mesh_terms: D000268:Adhesiveness; D000537:Aluminum Oxide / Q000737:chemistry; D002484:Cementation; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: C433205:Calibra; D003188:Composite Resins; D003764:Dental Materials; C483701:Rely X Unicem; D019279:Resin Cements; C501891:Tetric EvoCeram; C530542:clearfil esthetic cement; D014867:Water; D003776:Dental Porcelain; D012822:Silicon Dioxide; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide